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991.
Shanghai is a cosmopolitan city and one of the most important economic centers in China, but is saddled with serious environmental problems resulting from a recent industrial transformation. This paper examines the interactive relationships between economic growth, eco-efficiency of urban metabolism, and environmental performance of the Shanghai metropolitan area since the 1990s using 15 indicators. This study has revealed an enhanced eco-efficiency of water and energy use as well as an improved overall environmental quality in the central urban districts of Shanghai. Both TGDP (total GDP) and GDP per capita increased rapidly at the annual rate of 16.28% and 15.91%, respectively. In contrast, energy consumed per 10000RMB YUAN GDP (ECG), water consumed per 10000RMB YUAN GDP (WCG), wastewater discharged per 10000RMB YUAN GDP (WWDG), and waste gases emitted per 10000RMB YUAN GDP (WGEG) decreased at the annual rate of 9.34%, 10.69%, 14.57%, and 8.52%, respectively. The rapid decline in ECG, WCG, WWDG, and WGEG indicates an enhanced eco-efficiency of urban metabolism. However, uncontrolled emission of wastes from domestic instead of industrial sources adversely affected the overall environmental quality. In addition, suburban areas have undergone rapid economic growth at the cost of human health deterioration, as measured by mortalities and relative mortality ratios of three major diseases (tumor, respiratory disease, and trauma/toxicosis). With Shanghai serving as the "locomotive" driving the economy of the Yangtze River Basin, effective pollution control policies and a network of regional coordination are urgently needed in the globalization and ecological security of the entire area.  相似文献   
992.
The study focuses on understorey-overstorey plant community dynamics in a dry tropical forest to facilitate appropriate management decisions. We compare community composition and species diversity of the understorey vegetation among five dry tropical forest sites in northern India. A total of 1500 quadrats distributed over 15 one-ha permanent plots in five sites differing in the degree of disturbance, were used to enumerate the understorey tree species and the results were compared with overstorey tree layer. The non-metric multidimensional scaling (NMS) ordination revealed that human disturbance intensity, as well as the overall disturbance regimes, and soil water holding capacity controlled the organisation of dry tropical forest understorey composition through effects on soil organic matter. The alpha-diversity and its components decreased with increasing human disturbance intensity, reflecting utilisation pressure and decreased soil fertility, as also revealed by the analysis of overstorey tree layer. There was a significant positive relationship between overstorey and understorey diversity. Results suggest that in the future, the existing understorey tree communities may replace the current dry tropical forest communities under prevailing environmental conditions. The study also asserts that the rate of species accumulation will be greater in more disturbed sites as well as at small spatial scale within each disturbance level.  相似文献   
993.
生态环境脆弱地区油气田开发生态保护措施探讨   总被引:1,自引:1,他引:0  
我国许多油气田处于生态环境脆弱地区,石油开采以及油气集输、储运等工程对生态环境的影响非常突出。文章依据生态保护的原则提出了油气田开发规划、设计、施工以及施工后几个阶段应当采取的生态保护措施,同时还提出了施工结束后的一些生态恢复措施,以供借鉴。  相似文献   
994.
湛江市农村居民点用地面积变化及驱动力分析   总被引:4,自引:0,他引:4  
利用湛江市1996—2005年农村居民点用地面积数据及相关社会经济数据,在分析农村居民点用地面积变化的基础上,采用主成分分析法对其进行了驱动力分析。结果表明,近十年来湛江市农村居民点用地总面积呈逐年上升的趋势,而农村居民点人均用地面积总体呈减少趋势。湛江市农村居民点用地面积增加主要集中在徐闻、吴川和市区。湛江市农村居民点用地面积变化主要受农村人口增长、农村经济发展、农业结构调整、农村交通发展和乡镇企业发展等因素的影响。  相似文献   
995.
Abstract: The increase of coverage of forest/vegetation is imperative to improve the environment in dry‐land areas of China, especially for protecting soil against serious erosion and sandstorms. However, inherent severe water shortages, drought stresses, and increasing water use competition greatly restrict the reforestation. Notably, the water‐yield reduction after afforestation generates intense debate about the correct approach to afforestation and forest management in dry‐land areas. However, most studies on water‐yield reduction of forests have been at catchment scales, and there are few studies of the response of total evapotranspiration (ET) and its partitioning to vegetation structure change. This motivates us to learn the linkage between hydrological processes and vegetation structure in slope ecosystems. Therefore, an ecohydrological study was carried out by measuring the individual items of water balance on sloping plots covered by different vegetation types in the semiarid Liupan Mountains of northwest China. The ratio of precipitation consumed as ET was about 60% for grassland, 93% for shrubs, and >95% for forestland. Thus, the water yield was very low, site‐specific, and sensitive to vegetation change. Conversion of grassland to forest decreased the annual water yield from slope by 50‐100 mm. In certain periods, the plantations at lower slopes even consumed the runon from upper slopes. Reducing the density of forests and shrubs by thinning was not an efficient approach to minimize water use. Leaf area index was a better indicator than plant density to relate ET to vegetation structure and to evaluate the soil water carrying capacity for vegetation (i.e., the maximum amount of vegetation that can be supported by the available soil water for an extended time). Selecting proper vegetation types and plant species, based on site soil water condition, may be more effective than the forest density regulation to minimize water‐yield reduction by vegetation coverage increase and notably by reforestation. Finally, the focuses in future research to improve the forest‐water relations in dry‐land areas are recommended as follows: vegetation growth dynamics driven by environment especially water conditions, coupling of ecological and hydrological processes, further development of distributed ecohydrological models, quantitative relation of eco‐water quota of ecosystems with vegetation structures, multi‐scaled evaluation of soil water carrying capacity for vegetation, and the development of widely applicable decision support tools.  相似文献   
996.
北京市近郊区乡村景观规划方法初探   总被引:12,自引:0,他引:12  
以北京西北近郊白家疃村为例 ,分析了乡村景观的现状和动态演变的特征 ,重点探讨了乡村景观规划的原则和方法 ,并提出了白家疃村景观规划方案和设计要点  相似文献   
997.
黄河下游堤防保护范围的研究   总被引:1,自引:1,他引:0  
李娜  杨磊  刘树坤 《灾害学》2001,16(1):12-17
历史上,黄河山东段曾多次泛滥,为了解定黄河下游堤防的保护范围及保护范围内的洪水风险,本文利用二维不规则网格非恒定流洪水仿真模型,研究了黄河下游山东段堤防的保护范围,该研究对于黄河下游堤防建设及两岸地区的防洪灾害具有重要的指导意义。  相似文献   
998.
浙江省梅汛期洪涝灾情分析和预测   总被引:1,自引:0,他引:1  
通过所构设的雨涝强度、雨涝影响面积等统计量来估计浙江省梅汛期的灾情,有较高的准确率,能估计出极端情况,为灾害评估工作提供了新的思路。  相似文献   
999.
Water with high nitrate concentration (NO3 ) is unfit for human consumption, especially when its concentration exceeded the threshold limit (50 mg/l) recommended by the health authorities such as the World Health Organization (WHO). In Jordan, there is a great concern for determination and monitoring organic and inorganic pollutants that may reach groundwater. Nitrate is highly mobile and present in domestic, agricultural and industrial waste in Jordan, and thus this study focused initially on nitrate as both a contaminant of concern and as an indicator of potential groundwater contamination. The present study determined the extent of nitrate contamination in groundwater in the study area and examined the likely sources of NO3 . A total of 248 groundwater samples were collected from 16 wells in different sites of Al-Hashimiya area, Zerqa Governorate, Jordan, and investigated for NO3 concentrations. Moreover, measurements of temperature, electrical conductivity and pH were carried out in the field. Analysis was carried out according to the methods described by the American Public Health Association (APHA). Results showed that there was a dramatic increasing in NO3 concentrations from the year 2001 to 2006 for some selected wells in the present study. NO3 concentration in 2006 was ranged from 10 to 330 mg/l with an average of 77 mg/l. Overall, groundwater had elevated nitrate concentration with 92% of the samples containing more than 20 mg/l NO3 , indicating the influence of human activities. This study has shown that there is a strong correlation between the nitrate concentration and the wastewater effluents as a source of pollution.  相似文献   
1000.
上海市地表灰尘中PAHs季节变化与功能区差异   总被引:5,自引:3,他引:2  
程书波  刘敏  欧冬妮  高磊  王丽丽  许世远 《环境科学》2007,28(12):2789-2793
研究了上海市中心城区地表灰尘中多环芳烃(PAHs)的季节变化与功能区差异,并探讨了这种变化特征的原因.结果表明,上海市中心城区地表灰尘中PAHs累积水平具有显著的季节变化,PAHs总量和组分均表现出冬季含量高于夏季的特征.冬季样品中PAHs含量为9 176~32?573 ng·g-1,平均值为20 648 ng·g-1;而夏季PAHs含量为6?875~27?766 ng·g-1,平均值仅为14?098 ng·g-1.PAHs组分也表现出相似特征,冬季含量为50(二氢苊)~3 162 ng·g-1 (茚并[1,2,3-c,d ]芘),夏季含量为3(苊)~1 485 ng·g-1 (茚并[1,2,3-c,d ]芘).各个功能区地表灰尘PAHs含量的差异明显.冬季最高值出现在工业区(31 163 ng·g-1)、商业区(24 932 ng·g-1)和交通要道(18 815 ng·g-1),最低值出现在公园(7 885 ng·g-1)和绿地(8 036 ng·g-1);夏季最低值出现在公园(7 942 ng·g-1),最高值出现在交通要道(14 528 ng·g-1)、工业区(14 247 ng·g-1)和商业区(11 523 ng·g-1).所有功能区样品中PAHs组分含量呈现出按环数或分子量的增加而逐渐升高的趋势.大城市地表灰尘中PAHs的季节变化与功能区差异与其来源密切相关,也受到各组分理化性质的影响.  相似文献   
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